[GBase 8s 教程]GBase 8s 时间/日期函数和操作符

日期/时间操做符

下表演示了基本算术操作符的行为(+,-,*,/等)：

类型1	操作符	类型2	返回类型	示例、说明
DATE	-	DATE	INTERVAL DAY TO DAY	date(‘2020-05-08’) - date(‘2020-05-01’) 值为7
DATE	-	DATETIME	INTERVAL DAY TO DAY	date(‘2020-05-08’) - datetime(2020-05-01 12:00:00) year to second 值为7
DATE	+ -	INTERVAL DAY TO DAY	DATETIME	date(‘2020-05-08’) + interval(10) day to day 值为2020-05-18 00:00:00
DATE	+ -	NUMBER	DATE	date(‘2020-05-08’) - 10 值为2020-04-28
DATETIME	-	DATE	INTERVAL	current year to second - date(‘2020-05-08’)值为 0 20:46:57 当前时间为2020-05-08 20:46:57，将DATE类型转换为当天00:00:00
DATETIME	-	DATETIME	INTERVAL	current year to second - datetime(2020-05-01 12:58:58) year to second 值为 7 07:50:05
DATETIME	+ -	INTERVAL	DATETIME	current year to second - interval(03:04:05) hour to second 值为2020-05-08 17:46:02
DATETIME	+ -	NUMBER	DATETIME	current year to second + 2/24/60 值为2020-05-08 21:07:17 当前时间为2020-05-08 21:05:17，2/24/60 (2分钟)
INTERVAL	+ -	INTERVAL	INTERVAL	interval(03:04:05) hour to second + interval(3) hour to hour 值为 6:04:05
INTERVAL	* /	NUMBER	INTERVAL	interval(03:04:05) hour to second * 4 值为12:16:20

日期/时间函数

函数	返回类型	描述	示例	结果
DAY(date/datetime)	NUMBER	返回第几天	DAY(today)	8 今天为2020-05-08
MONTH(date/datetime)	NUMBER	返回月份	MONTH(today)	5 今天为2020-05-08
YEAR(date/datetime)	NUMBER	返回年份	YEAR(today)	2020 今天为2020-05-08
WEEKDAY(date/datetime)	NUMBER	返回当周几	WEEKDAY(today)	5 今天为2020-05-08周五, 周日返回为0
DATE(date_string)	DATE	返回字符串日期	date(‘2020-05-08’)	2020-05-08
TODAY	DATE	返回当前日期的日期值	TODAY	2020-05-08
CURRENT [first TO last]	DATETIME	返回当时日期的日期时间值	CURRENT YEAR TO SECOND	2020-05-08 21:22:09
SYSDATE [first TO last]	DATETIME	返回当时日期的日期时间值	SYSDATE YEAR TO SECOND	2020-05-08 21:22:09
MDY(Month,Day,Year)	DATE	返回指定的日期值	MDY(5,8,2020)	2020-05-08
DATETIME(date/datetime) first TO last	DATETIME	返回表达式代表的日期时间值	datetime(2020-05-08 20:10:50) year to second	2020-05-08 20:10:50
INTERVAL(date/datetime) first TO last	INTERVAL	返回表达式代表的间隔值	interval(3 03:04:05) day to second	3 03:04:05
EXTEND(date/datetime,[first TO last])	DATETIME	返回经过表达式调整的日期时间值	extend(current year to second, hour to second)	21:33:06